Flights from St. Louis to Cartagena lean towards being more expensive in November. Prices are generally better when you fly from St. Louis to Cartagena in June, with the cheapest ticket starting at $646.
Leaving on a Monday is a viable option for saving on travel. Heavily demanded days of the week can typically drive up the prices you see. Booking your travel for a less competitive day can save up to 74% on the overall cost on flights from St. Louis to Cartagena.
Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from St. Louis to Cartagena as you normally would.